<template>
    <div>
        <h1>当前求和为： {{sum}}</h1>
        <select v-model.number="n">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </select>
        <button @click="increment">+</button>
        <button @click="decrement">-</button>
        <button @click="incrementOdd">当前求和为奇数再加</button>
        <button @click="incrementWait">等一等在加</button>
   </div>
</template>

<script>
    export default {
        name: 'Count',
        data() {
            return {
                n:1, //用户选择的数字 
                sum:0 //当前的和
            }
        },
        methods: {
            increment() {
                this.sum += this.n
            },
            decrement() {
                this.sum -= this.n
            }, 
            incrementOdd() {
                if(this.sum %2 ){
                    this.sum += this.n
                }
            }, 
            incrementWait() {
                setTimeout(()=>{
                    this.sum += this.n
                })
            },
        }
    }
</script>

<style lang="css"> 
    button {
        margin-left: 5px;
    }
</style>